SPRINGFIELD — A key provision of the new agreement between the town of Springfield and the developers of the proposed biomass plant in North Springfield involves a $3 million payment to build a new access road to serve the project.

But the $3 million would be part of a tax stabilization agreement between the town and the North Springfield Sustainable Energy Project, and would in essence be an advance payment toward those taxes, Town Manager Robert Forguites said Tuesday.

Forguites said the $3 million would not be in addition to property taxes the 35-megawatt project is expected to pay. The project has been estimated as high as $170 million to half that, so until the project is built and assessed, it is difficult to say how much it would ultimately pay in taxes, Forguites said.

Forguites said he expected the biomass plant, if built, would increase Springfield’s Grand List by 15 percent. He said it is currently at about $660 million.

The Springfield Select Board voted 4-1 in favor of the memorandum of understanding between the town and North Springfield Sustainable Energy Project, a joint venture of Winstanley Enterprises and Weston Solutions.

Voting against the agreement was Select Board member Michael Knoras, who told fellow board members at Monday night’s meeting he wanted some changes made in the agreement. Knoras couldn’t be reached for comment Tuesday.

Select Board member David Yesman said he had originally proposed the board approve the agreement conditionally, with some changes incorporated regarding protection of the aquifer in North Springfield, with final approval set for the board’s next meeting in mid-July.

But Yesman said Tuesday he withdrew his motion because he realized that the town had no power to enforce what he was seeking — that is up to the Agency of Natural Resources.

Forguites said the project would give $1.5 million upfront to the town to build the access road. “They would still pay taxes under the tax stabilization plan, which has not been finalized yet,” he said.

The $3 million would be a credit toward its first 10 years of taxes, he said.

“They would still be paying a sizeable amount of taxes,” Forguites said.

At Monday night’s meeting, at least one resident urged the board not to enter into a tax stabilization agreement with the project, noting it wasn’t a “clean” industry and wouldn’t create many jobs.

Forguites said the Southern Windsor County Regional Planning Commission was working on its own memorandum of understanding with the project to address regional issues such as truck traffic and access routes.

The biomass developers already have an option on one of two properties they would need to build the new access road from Route 10 to the North Springfield Industrial Park.